Conventionally known resist materials are generally polymeric materials capable of forming amorphous thin film. For example, a solution of poly(methyl methacrylate) is applied on a substrate to form a thin resist film, which is then irradiated with ultraviolet rays, far ultraviolet rays, electron beams, extreme ultraviolet rays (EUV), X-rays, etc., to form line patterns having a width of about 0.1 μm.
The polymeric resist compounds generally have a molecular weight as large as about 10,000 to 100,000 and a broad molecular weight distribution. Therefore, in a lithographic fine process using the polymeric resist compounds, the surface of the fine patterns is roughened, thereby making it difficult to control the dimension of patterns and reducing the product yield. Thus, the conventional lithographic techniques using the known polymeric resist materials have limitations in fine processing. To produce finer patterns, there have been proposed various low-molecular resist materials.
Known non-polymeric resist materials include, for example, (1) positive- or negative-type resists derived from fullerene, (2) positive- or negative-type resists derived from calixarene, (3) positive-type resists derived from starburst-type compounds, (4) positive-type resists derived from dendrimer, (5) positive-type resists derived from dendrimers/calixarene, (6) positive-type resists derived from highly branched starburst-type compound, (7) positive-type resists derived from ester linkage-containing starburst-type compound mainly constituted by a trimesic acid structure, (8) negative-type resists derived from cyclic polyphenol compound, and (9) negative-type resists derived from polyphenol compound.
The resist materials (1) are good in the etching resistance but not practical in the coating properties and sensitivity (Patent Documents 1 to 5). The resist materials (2) are excellent in the etching resistance, but fail to form satisfactory patterns because of a poor solubility in a developing solution (Patent Documents 6 to 8). The resist materials (3) have a low heat resistance and therefore tend to cause the distortion of patterned images during the heat treatment after exposure to light (Patent Documents 9 to 11). The resist materials (4) are less practicable because a complicated production process is required and the distortion of patterned images due to their low heat resistance occurs during the heat treatment after exposure to light (Non-Patent Document 1). The resist materials (5) are less practicable because a complicated production process is required and the raw materials are expensive (Patent Documents 12 and 13). The resist materials (6) are less practicable because a complicated production process is required and the raw materials are expensive. The resist materials (7) are less practicable because the distortion of patterned images due to their low heat resistance is likely to occur during the heat treatment after exposure to light and the adhesion to substrates is poor (Patent Document 14). The resist materials (8) and (9) are insufficient in the amorphous properties and etching resistance, and therefore, the improvement is still demanded (Patent Documents 15 to 17).    [Patent Document 1] JP 7-134413A    [Patent Document 2] JP 9-211862A    [Patent Document 3] JP 10-282649A    [Patent Document 4] JP 11-143074A    [Patent Document 5] JP 11-258796A    [Patent Document 6] JP 11-72916A    [Patent Document 7] JP 11-322656A    [Patent Document 8] JP 9-236919A    [Patent Document 9] JP 2000-305270A    [Patent Document 10] JP 2002-99088A    [Patent Document 11] JP 2002-99089A    [Patent Document 12] JP 2002-49152A    [Patent Document 13] JP 2003-183227A    [Patent Document 14] JP 2002-328466A    [Patent Document 15] JP 11-163863A    [Patent Document 16] JP 2003-207893A    [Patent Document 17] JP 2004-334106A    [Non-Patent Document 1] “Proceedings of SPIE”, vol. 3999 (2000), pp. 1202-1206